Inhalation device

ABSTRACT

A method and device for dispensing a particulate medicament material from a container. The container provided with at least one powder outlet is rotated by pneumatic means about an axis of the container. The axis of rotation is caused to precess so as to describe a path of precession which is contained within a generally conical surface of precession, and the axis of rotation of the container is at an angle to the axis of the generally conical surfaces of precession. This causes the walls of the container to undergo repeated changes in radial acceleration with respect to the axis of the generally conical surface of precession, which changes of acceleration are of sufficient magnitude to overcome the centrifugal and cohesive forces which hold the particles of powder in place upon the wall of the container.

nited States Patent Altounyan et a1. June 13, 1972 [54] INHALATIONDEVICE [72] Inventors: Roger Edward Collingwood Altounyan, [56]References Cited Wilm l Eng n H ry Ho ll, UNITED STATES PATENTSdeceased, late of Castle Donnington, En-

gland Eunice Cockbum Howe, executrix 2,573,918 1 1/195] MCCUlSlOll128/206 Assignee: Fisons, Limited, London, England Filed: June 18, 1969Appl. No.: 871,468

Related US. Application Data Continuation-in-part of Ser. No. 745,774,July 18, 1968, which is a continuation-in-part of Ser. No. 532,271,March 7, 1966.

Foreign Application Priority Data [1.8. CI ..l28/266 ..A6lm 15/00 Fieldof Search 128/266, 206, 208

Primary Examiner-Robert W. Michell Attorney-Wenderoth, Lind & Ponack[57] ABSTRACT A method and device for dispensing a particulatemedicament material from a container. The container provided with atleast one powder outlet is rotated by pneumatic means about an axis ofthe container. The axis of rotation is caused to precess so as todescribe a path of precession which is contained within a generallyconical surface of precession, and the axis of rotation of the containeris at an angle to the axis of the generally conical surfaces ofprecession. This causes the walls of the container to undergo repeatedchanges in radial acceleration with respect to the axis of the generallyconical surface of precession, which changes of acceleration are ofsufficient magnitude to overcome the centrifugal and cohesive forceswhich hold the particles of powder in place upon the wall of thecontainer.

25 Claims, 10 Drawing Figures PATENTEmun I3 1312 3.669.113

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INVENTORS ROGER E.C. ALTOUNYAN HARRY HOWELL ATTORNEYS PATENTEDJuu 13I972 SHEET 2 UF 5 INVENTORS ROGER E.C. ALTOUNYAN HARRY HOWELL BY M fl 7MATTORNEYS PATENTEDJlm 13 I972 3.669.113

SHEET 3UP 5 I v /-4 I I 3 q \Sa IO FIG 4 INVENTOR ROGER E.C.ALTOUNYANHARRY HOWELL BY e ATTORNEY PATENTEDJUN 13 I972 sum u or 5 FIG.6

FIGJO INVENTORS ROGER E.C.ALTOUNYAN HARRY HOWELL ATTORNEYS INHALATIONDEVICE This application is a continuation-in-part of our applicationSer. No. 745,774, filed July 18, 1968, which in turn was acontinuation-in-part of our application Ser. No. 532,271, filed Mar. 7,1966.

The present invention relates to a method whereby particulate medicamentmaterials may be dispersed from a container using a fluidizationtechnique. The invention also provides devices for use in the method ofthe invention.

Accordingly, the present invention provides a method for dispensing aparticulate medicament material from a container which comprisesrotating a container provided with at least one powder outlet bypneumatic means about an axis thereof and causing the axis of rotationto precess so as to describe a path of precession which is containedwithin a generally conical surface of precession. By generally conicalis meant a surface of precession which is a cone or frusto-cone ofprecession. The axis of rotation of the container being at an angle tothe axis of the cone or frusto-cone of precession. By the expression atan angle to is meant an axis of rotation which intersects the axis ofthe cone or frusto-cone of precession as well as an axis of rotationwhich does not intersect said axis of the cone or frusto-cone ofprecession. The walls of the container undergo repeated changes inradial acceleration with respect to the axis of the cone or frusto-coneof precession, which changes of acceleration are of sufficient magnitudeto overcome the centrifugal and cohesive forces which hold the particlesin place upon the wall of the container.

We believe that during the motion generated by the method of theinvention any point on the wall of the container executes a motion of atrochoidal nature in the radial plane of the cone or frusto-cone ofprecession. The trochoidal motion may be epitrochoidal orhypotrochoidal. As the container rotates, particulate material iscentrifuged against the container wall and is held in place therebyfrictional and cohesive forces. During the trochoidal motion theparticles are subjected to several changes in radial acceleration of thewall of the container. If the acceleration of the wall of the containeraway from the axis of the cone or frusto-cone of precession issufficiently great, the forces holding the particles in place upon thewall are overcome. The particles then leave the wall and adopt freeflight within the container whose walls continue to move along thetrochoidal curve. The particles later impinge upon the container wall ata different point to that at which their free flight was initiated. Itis believed that, since the containers axis of rotation is inclined tothe axis of the cone or frusto-cone of precession, the particles impingeupon the container wall at a point displaced along the axis of thecontainer. The particles thus undergo fluidization within the containerand also axial feed along the container.

The occurrence of fluidization and the rate and extent of movement ofparticles within the container are dependent upon a number ofinter'related factors, such as the relative diameters of the containerand the cone or frusto-cone of precession at the base of the container,the speed of rotation of the container, the relative angular speeds ofrotation of the container and its precession, the size of the includedangle of the cone or frusto-cone of precession, the nature ofthe-particulate material within the container and its interaction withthe material of the container wall.

The motion generated by the method of the invention consists in essenceof a circular sequence of cusps leading into one another at nodes, whichmay be transition curves, simple points or small loops linking one cuspto the next. The magnitude of the variations in radial accelerationundergone by a point on the container wall depends upon the number ofcusps which occur during each revolution of the container about the axisof precession and upon the difference between the apogee and perigee ofthe locus of the point on the container wall as it moves around the axisof precession. These variables are themselves functions of the factorsreferred to above and may be varied over a wide range according to theform and size of the device used to generate the required motion.However, the energy available to fluidize powder on the container wallduring the traversal of each cusp is inversely proportional to thenumber of nodes occurring per rotation of the container axis about theaxis of precession, or the nodal number as this ratio will be termedhereinafter. At excessively high or low nodal numbers fluidizationwithin the container may be inadequate and we prefer that the nodalnumber should be from 2 to 25, preferably 3 to 10, to achievesatisfactory fluidization. The nodal number need not be an integer. Aswill be shown later. the nodal number is a function of the dimensions ofthe device generating the motion. Having established suitable dimensionsfor a device so as to achieve the desired nodal number, the differencebetween the apogee and perigee of the locus of a given point on the wallof the container may be varied to secure fluidization. This variationmay be achieved by altering the size of the included angle of the coneor frusto-cone of precession and/or by altering the radius of thecontainer and/or by altering the distance of the container from the apexor notional apex of the cone or frusto-cone of precession, whicheffectively alters the diameter of the cone or frusto-cone of precessionat the container. A decrease in the container radius or an increase inthe distance between the container and the apex of the cone orfrusto-cone promotes fluidization. It will of course be appreciated thatthese factors are inter-related with the nodal number and thatfluidization may be achieved by many permutations of these factors.However, if the included angle of the cone or frusto-cone of precessionis high, say 60 or more, then the rate of axial feed of particles withinthe container is extremely rapid. Whilst movement of particles along theaxis of the container will occur at very small cone angles, e.g. lessthan about 0.5, such movement will be relatively slow. An included angleof about 1 to preferably about 2, will usually give an adequate rate ofmovement, provided that adequate fluidization occurs.

The other factors referred to above are not readily susceptible to suchgeneralized statements in view of their close interrelationship andtheir dependence upon the size and nature of the device generating themotion and its intended use.

The motion required by the method of the invention may be generated by anumber of fonns of device. For example, the container may be mountedupon a rigid shaft having a universal joint therein. The free end of theshaft is rotatably mounted by means of a conventional lubricated bearingassembly, such as a ball or roller race or a bush type bearing. Betweenthe container and the universal joint is a bearing adapted to retain theangle of the cone of precession of the shaft within the desired range.This may take the form of an annular ring surrounding the shaft andwhich engages with a bearing shoulder on the shaft (this type of devicegenerates hypotrochoidal motion), or may take the form of an annularshoulder on the shaft which shoulder is provided with a dependentannular bearing skirt whose inside surface engages with the outsidebearing surface of a fixed annular ring of smaller diameter (this typeof device generates epitochoidal motion). In an alternative form, theuniversal joint may be replaced by a flexible shaft. Furthermore, byintroducing assymetric flexibility into the shaft, for example by makingit with a polygonal cross-section e.g. a triangular, square or hexagonalsection, it may not be necessary to provide the restraining bearing.

The motion may also be generated by a rigid shaft carrying the powdercontainer rotating within two spaced annular bearing rings of differentdiameters. The annular bearing rings may take the form of a taperedbearing tube where contact between the shaft and bearing occurs at thetop and bottom extremes of the tube, and the term bearing ring is usedherein to denote not only an annular bearing surfaced member, but alsoan annular area of contact between a shaft and a bearing surface. Such abearing tube may be provided with a ridge or an inserted protruding lipat its top and/or bottom extremes to provide the contacting bearingrings or may be concaved between its ends to achieve the same effect.Alternatively the bearing rings may be of the same diameter and theshaft be tapered. It will also be appreciated that the shaft may be thestationary member and that the powder container may be carried by thetapered bearing tube. The difference in diameter between the shaft andthe bearing rings afiect the nature of the motion generated.

During the motion generated by the above devices, each contact betweenthe shaft and a bearing ring will generate a motion wherein the ratio ofthe frequency of rotation of the container about the axis of the cone orfrusto-cone of precession to the frequency of rotation of the containerabout its own axis (or the frequency ratio as this ratio will be termedherein) is dependent on the ratio of the diameter of the moving memberto the difference in diameters of the moving and stationary members. Thegreater the difference in diameters between the moving and stationarymembers, the more eccentric and in general more dominant will be thetrochoidal motion generated by that contact. Where the moving memberrotates within the stationary member, the nodal number is one more thanthe frequency ration, whereas where the moving member rotates around theoutside of the stationary member, the nodal number is one less than thefrequency ratio. Each bearing ring, or its equivalent, generates its owntrochoidal motion and, where there are two bearing rings, these motionscombine to yield an overall resultant motion for the free end of theshaft.

It is desirable that the effect of the non-dominant motion should eitherbe minimized or should complement the motion generated by the dominantbearing ring. Whilst the latter may be achieved by ensuring that thenodal number of the nondominant motion is an integer multiple of, e.g.2, 3 or 4 times, the nodal number of the dominant motion, such an exactrelationship may prove difficult to achieve in practice. We thereforeprefer to minimize the effect of the non-dominant motion. Usually thenon-dominant motion is generated by the smaller bearing ring and theeffect of the motion of this ring may be minimized by decreasing thetotal clearance between the shaft and this bearing ring. This increasesthe nodal number of the motion generated and we have found that ingeneral, if the nodal number at a point on the container wall of thenon-dominant motion is in excess of 15, preferably in excess of 30, theeffect of this motion is reduced to a satisfactory extent.

it will be appreciated that the distance between the bearing rings andthe clearances between the shaft and the bearing rings will determinethe included angle of the cone or frustocone of precession.

A particularly preferred form of bearing ring and shaft for generatingthe motion required by the method of the invention is one wherein arigid substantially uniform cylindrical shaft is journalled in aninternally tapered bearing tube, notably one wherein the bearing tubehas an internal diameter at its inner end (i.e. that end housing thefree end of the shaft) which is smaller than the internal diameter atits outer end. It is especially. preferred that the shaft be thestationary member and that the bearing tube be rotatably mounted on theshaft. With such a device, fluidization within a container mounted onthe bearing tube will occur when the changes in radial accelerationundergone by the container wall due to the motion generated by thedominant contact between the shaft and bearing are sufficiently large toovercome not only any conflicting acceleration generated by thenon-dominant contact and the cohesive forces amongst the particles andbetween the particles and the container wall, but also overcome thecentrifugal forces generated during the motion. In an ideal case theeffects of the non-dominant motion would be nil and, if one ignoresinter-particle forces, we have found that fluidization in such an idealcase will occur at a given point on the container wall when the taperedbearing tube is rotated in rolling contact upon the stationary shaft ifthe expression:

a/h (R/R-r) R is satisfied, a is the distance of the base of theparallel walled section of the container from the non-dominant contactbetween the shaft and bearing, 11 is the distance between the dominantand non-dominant contacts between shaft and bearing, R is the internalradius of the bearing at the dominant contact, r is the radius of theshaft and R is the internal radius of the container at a distance a fromthe non-dominant contact between the shaft and bearing. Usually thelimiting case for fluidization will be at the base of the powdercontainer where this has a flat bottom and parallel side walls. However,where the container has a rounded bottom, the limiting case may be atsome point above the base, for example at the start of the parallelwalled portion thereof. The limiting case may be readily ascertained.

It must be emphasized that the above expression represents the minimumrequirements for fluidization under the conditions specified. However,inter-particle forces must also be overcome and the non-dominant motionmay conflict with the dominant motion to reduce the fluidizing forcesgenerated. The left hand side of the above expression must therefore inpractice exceed the right hand side by an amount which will varyaccording to the above factors. In practice, therefore, the approximatedimensions for a device established from the above expression mayrequire optimisation by experimentation. It will be appreciated that asatisfactory device for present use may be constructed using a widerange of dimensions in a number of permutations. However, various of thedimensions of this preferred form of device for present use may belimited by certain factors, thus reducing the number of possiblepermutations which may be made. For example, the energy available in thedriving gas stream will impose limitations on the possible size of thedevice as may the strength of the materials used to construct thedevice; and, where the device is to be carried in the pocket of a user,it clearly cannot exceed, say, 6 inches in total length. Furthermore,the powder container to be used in the device may be of a standardspecified form and size since medicaments are usually put up in standardgelatin capsules holding, say, 20 mgs of drug. For efficient operationthe capsule is filled with powder only to one-half to one-third of itstotal capacity.

In the form of device where a shaft is journalled in a tapered bearingtube, it is preferred that the non-dominant contact between the shaftand bearing generate a motion at the container wall having a nodalnumber in excess of 15, preferably in excess of 30, and that thedominant contact generate a motion at the container wall having a nodalnumber of from 2 to 25, e.g. 3 to 10 notably 5 to 7. A suitable motionmay, for example, be generated by rolling contact between a cylindricalshaft and a tapered bearing tube which has an internal diameter at oneend which is from 1.5 to 6 percent, preferably 2.5 to 9 percent, notablyabout 3.5 percent, greater than the diameter of the shaft and aninternal diameter at its outer end which is equal to the diameter of theshaft plus from 1.3 to 3.5 percent, notably about 2.5 percent, of theinternal length of the bearing tube. In general it is desirable to useas fine a rigid shaft as possible, for example a drawn wire shaft ofabout 0.080 inches diameter may be used in devices powered by humaninhalation. Typically, the bearing tube may have an internal lengthwhich is 4 to 10, preferably about 7, times the diameter of the shaft.

It is also preferred that the shaft have a rounded free end which bearsagainst the flat closed end of the bearing tube. The free end of theshaft may be of frusto-conical shape, preferably terminating in anhemispherical tip, which tip has a diameter approximately half that ofthe shaft.

The expression a/h (R /R--r) R quoted above is in relation to a devicewhere a tapered bearing tube is rotatably mounted upon a rigidcylindrical shaft. However, where the bearing tube is stationary and itis the shaft which rotates in rolling contact with the bearing,fluidization of powder within a container mounted on the shaft willoccur under the idealized conditions when a/h (FIR-r) R,; a, h, r, R andR having the same values as quoted earlier.

In a further form of device, the use of an integral restraining bearingsurface and of a shaft journalled in a bearing tube are combined byproviding the container carrier with a short tapered shaft which ismounted centrally within a dependent cylindrical sleeve having aninternal dry friction bearing surface. The short shaft is journalled ina tapered recess in the end of a rigidly mounted cylindrical boss orshaft. The dimensions of the recess and of the short shaft are such thatthe dry friction bearing surface on the dependent skirt can bear againstthe exterior of the rigidly mounted boss or shaft to provide the drivewhereby the freely rotating short shaft is caused to precess.

In the forms of the shaft and bearing configuration described above, thecontact between the shaft and that bearing ring generating the dominantmotion must be frictional in order that precession may take place. It ispreferred that the contact be rolling and, in order to ensure uniformmotion of the container walls, that this rolling contact be maintainedat substantially all times during the motion. Where two bearing ringsare used to generate the motion, the contact between the shaft and thenon-dominant bearing ring need not be frictional and in some cases itmay be feasible to lubricate this bearing ring, but not the other, inorder to minimize any motion generated by this bearing ring.

In the mechanisms described above, precession has been achieved by thefact that the axis of the rotating member upon which the container ismounted sweeps out a conical or as near conical surface as can beachieved in practice; that the rotating member or an integral partthereof bears against a stationary member; and that the contact betweenthe rotating and the stationary members is frictional, preferably arolling contact.

Accordingly, from a further aspect the invention provides an apparatusfor use in the method of the invention which comprises a bearing memberhaving an annular bearing surface and a shaft journalled loosely in thebearing member, one of said bearing and said shaft being stationary, theother being adapted to be rotated by pneumatic means and to receive acontainer, the rotatable member being capable of being displaced duringrotation thereof at an angle about the axis of the stationary member,the annular bearing surface of the bearing member and the shaft or anintegral part thereof being adapted to contact one another in africtional contact during rotation of the rotatable member. In manycases the design of the stationary and rotatable member will be suchthat the rotatable member inherently adopts at all times a positionwhere its axis is displaced at an angle to the axis of the stationarymember, e.g. as is the case where a stationary shaft carries a loosefitting bearing tube which even at rest will tend to adopt a cantedposition vis a vis the shaft. However, in some cases, the rotatablemember may adopt a substantially coaxial position with respect to thestationary member when at rest, as is the case with a flexible shaftsurrounded by a restraining bearing ring as described above, yet duringrotation may be deflected or whip so that the rotating member and thestationary bearing surface may come into contact to generate the desiredprecession.

Other mechanisms may readily be devised, such as epicyclic gear systemsand the like, which will cause the container to rotate and precess inthe manner required. Thus, a further form of mechanism is a shaft freelyjournalled in a bearing, the requisite wobble in the rotation of theshaft being achieved by means of the repeated attraction and repulsionof magnets mounted in the housing or shaft and the bearing.Alternatively, the precession of the container axis within a cone orfrustocone of precession may be achieved by mounting the container at anangle in a cup provided with a vane or vanes, which cup is rotatablymounted off center on a boss provided with a vane or vanes, which bossis itself rotatably mounted. The passage of air past such an arrangementwould cause rotation of both the boss and the cup causing the axis ofthe container to rotate and precess in the desired manner. In these twoforms of device the shaft and bearing assemblies should not be inrolling contact, i.e. are in sliding contact, and may be lubricated toassist their relative rotation.

The invention thus also provides an apparatus for use in the method ofthe invention which comprises a rotatable member carrying means toreceive a container, which rotatable member is mounted by means of ashaft journalled within at least one bearing member and is adapted to berotated pneumatically and to process so that its axis of rotationdescribes a path contained within a cone or frusto-cone of precession,the axis of rotation of the rotatable member being at an angle to, butnot necessarily intersecting, the axis of the cone or frusto cone ofprecession.

As has been stated above, the rotatable member which is to carry thecontainer is to be rotated pneumatically, for example by a gas streamgenerated with a rubber squeeze bulb or merely by the inhalation of airby a human user. The pneumatically driven means may take any of theconventional forms, such as a propeller or turbine assembly. Suchpneumatically driven means will for convenience be denoted hereinafterby the general term vanes, although this term is intended to include notonly a plurality of vanes as with a turbine, but also a single vane aswith an Archimedian screw. The vanes may be mounted integrally with theshaft or bearing tube carrying the container, the container receivingmeans, the container itself, or where the shaft is jointed, as is thecase where it has a universal joint, the vanes may be mounted above orbelow the joint. It is usually preferred to have the vanes mountedintegrally with the container receiving means in the form of, say, apropeller and boss on the end of the shaft, or bearing tube, the bossbeing provided with means for receiving a container.

Usually the gas stream driving the device will flow past the powdercontainer. However, it may be desirable to prevent an excessive flow ofdriving gas past the container. It is therefore within the scope of thepresent invention to provide means for isolating the container from thedriving gas stream. This may be done for example by providing a shroud,e. g. a sleeve, around the container which effectively channels the gasstream away from the container. Alternatively where the container ismounted on a universally jointed shaft, that portion of the shaft whichis supported in the bearing means may be journalled in a chamberseparated from that part of the shaft carrying the container and the gasstream only through that chamber.

The powder container for present use may be of any shape or size suitedto the intended rate of dispensing and total weight of drug to bedispensed. However, it is preferred that the powder container be acapsule or cartridge, e.g. an hard gelatine capsule, notably one of thegelatine capsules which are of the accepted standard sizes for drug use,e.g. of 20 to mg capacity. Typical of such capsules are those gelatinecapsules of internal diameter about 6.3 mms. In order that themedicament powder within the container may be dispensed into theairstream flowing past the container, the container is provided with oneor more outlets for the powder. Conveniently, these take the form ofperforations in the wall of the container, which holes are preferablysymmetrically arranged around the wall. With a gelatin capsule it ispreferred that the holes be in a shoulder of the capsule and that theybe of from about 0.6 mms to about 0.65 mms in diameter. It will beappreciated that the container should be mounted in any device with theholes in the free end of the container.

The rotating member in devices for present use is provided with meansfor mounting a powder container thereon. This means is preferably suchthat the powder container is mounted co-axially with the axis aboutwhich the rotating member rotates and is held rigidly in place duringoperation of the device. This may be achieved by forming a recess in theend of the rotating member which recess is of similar configuration tothe powder container and receives the container in a push tight fit.Thus where the rotating member is provided with a terminal boss carryingpropeller blades, the boss may be cut with a cup shaped recess toreceive a medicament capsule in a push tight fit.

The stationary and rotating members used to generate the motion requiredby the invention will usually be mounted in an housing adapted to leadthe driving gas stream through the vanes by which the rotatable memberis to be rotated. This gas stream will also usually flow past the powdercontainer and the housing may therefore take the form of an elongatedtube within which the rotating and stationary member are mounted. Thestationary member is preferably mounted substantially co-axially withthe tubular housing and should be rigidly mounted since undue flexingthereof may cause malfunctioning of the device. The housing may also beprovided with other features which may be required for optimum operationof the device. Thus, where the powder container is to dispense powdercontinuously, means may be provided for supplying powder to thecontainer; means may be provided for generating the driving gas stream,e.g. a rubber squeeze bulb; or the housing may be provided with anon-return valve which permits the passage of gas through the device inonly one direction. As indicated below, the method of the invention isof especial use in dispensing powdered medicament into an air streamwhich is being inhaled. Particularly preferred devices for present useare therefore of a suitable size for convenient use, and are providedwith a tubular housing for the stationary and rotating members whichhousing is provided with a mouthpiece via which the user can inhale airthrough the device. The rotating and stationary members are preferablymounted within such an housing so that the vanes which are to rotate therotatable member lie between the intended position of the powdercontainer and the mouthpiece. It is also preferred to provide thehousing in devices which are to be driven by the inhalation of airtherethrough by a user with a constriction or venturi section in orderto increase the air flow rate past the powder container. It will usuallybe preferred to form the housing in two parts, one having the mouthpieceand the stationary and rotating members and the other having the venturisection and the air inlet. By this means the air inlet may be removed toprovide free access to the mounting for the powder container duringloading or unloading of the container. If desired, the housing may alsobe provided with means for piercing the powder container in situ withinthe device. It may also be desired to provide means, such as a shroud,by which powder issuing from the container may be prevented fromdepositing upon the contacting surfaces of the stationary and movingmembers.

The devices for use in the method of the invention may be made from anysuitable material such as metal, e.g. steel or aluminum, or a thermosetor thermoplastic synthetic resin, such as polystyrene, nylon,polyethylene, unreaformaldehyde resins and the like. The material usedwill depend upon the sacle on which the dispensing of powder is to becarried out and the magnitude of the forces generated. The bearingsurfaces may also be made from conventional materials. However, whereprecession is achieved by means of a frictional contact, for examplebetween a shaft and the bush within which it is mounted, such contactingsurfaces should not be self lubricating and preferably are made fromhigh friction materials.

The method of the invention finds widespread use wherever it is desiredto dispense medicament powders into an airstream. Thus, it may be usedto dispense antibiotic and like powders in a cloud for deposition on awound or skin infection. However, as indicated above, the method findsespecial use in the dispensing of medicament into an airstream which isto be inhaled. The method affords a means by which very fine particlesmay be administered deep into the lungs of a user and, where the deviceused is one powered by the users inhalation, delivers the powder in anamount proportional to the rate of inhalation and the total volume ofair inhaled, thus automatically regulating the release of medicamentaccording to the depth of inhalation.

The method may be used to dispense a wide variety of powderedmedicaments and the particles thereof may be of any shape and may beamorphous or crystalline in nature. However, the method of the inventionis of especial application in dispensing micronized powders notablythose of particle size less than 80 microns many of which have poor flowcharacteristics and may not be readily dispensed by other methods.

The method of the invention will be described by way of example inrelation to various forms of device which may be used to administerpowdered medicament by oral inhalation and with reference to theaccompanying drawings in which:

FIG. I is a longitudinal section through a simple form of device;

FIG. 2 is a longitudinal section through a preferred form of device;

FIG. 3 is a longitudinal section through a cap suitable for use with thedevice of FIG. 2;

FIG. 4 is a longitudinal section through an alternative form of thedevice of FIG. 2 wherein the shaft and bearing tube have beentransposed;

FIG. 5 represents an alternative form of bearing tube for use in thedevices of FIGS. 2 and 4;

FIG. 6 is a longitudinal section through an alternative form of a simpledevice for generating the motion required by the method of theinvention;

FIG. 7 is a longitudinal section through an alternative form ofthedevice of FIG. 6;

FIG. 8 is a diagrammatic longitudinal section through a furtheralternative form of the device of FIG. 6; and

FIGS. 9 and 10 are diagrammatic longitudinal sections through twofurther forms of bearing and shaft assembly which may be used togenerate the motion of the invention.

Referring now to FIG. 1, an inhalation device comprises a tubularhousing 1, one end of which, B, is adapted to be inserted in the mouth.Mounted co-axially with housing I is a shaft 2 having loosely androtatably mounted thereon a tapered bearing tube 5 carrying apropeller-like member 3 having blades 4. The propeller-like member 3 hasa cup-like receptacle therein adapted to engage and hold a perforatedcapsule 6 containing finely divided medicament.

When end B of housing 1 is inserted in the mouth and air is inhaledthrough the mouth, the resulting airstream causes the propeller-likemember 3 to rotate and precess about shaft 2 with the result that thefinely owdered medicament is fluidized in capsule 6, is dispensedtherefrom and passes with the airstream past blades 4 out of end B ofhousing 1 and into the mouth and respiratory tract of the user.

Referring now to FIG. 2, this form ofinhalation device comprises anhousing of approximately circular cross-section having a diameter ofabout 1.9 cm. and length of about 5 cm. and comprising two engagingmembers 7 and 8, housing member 8 being adapted for insertion into themouth and having passageways 9 therein to permit the passage of air.Mounted rigidly in and co-axially with housing member 8 is shaft 2 uponwhich is loosely and rotatably mounted tapered bearing tube 5 carryingpropeller-like member 3 having blades 4. Propellerlike member 3 has acup shaped receptacle adapted to receive and hold a capsule or containerof finely powdered medicament 6 which is pierced with holes in theshoulder of the free end thereof. The tip 10 of shaft 2 is conical inshape, having a cone angle of about 30", and terminates in asubstantially hemispherical portion having a diameter of about half thediameter of shaft 2.

Housing member 7 has in its end wall air passages 11 to permit thepassage of air and constricting member 12 which serves to constrict theair stream through the device and thus increase its velocity past thecapsule.

Through the end wall of housing member 7 extends locking member 13 whichis attached at its outer end to base piece 14. Between base piece 14 andhousing member 7 is a spring 15 which urges locking member 13 into anormally open position. Base piece 14 has a screw thread 16 whichengages in a similar screw thread 18 in cap 17 (shown in FIG. 3) to holdlocking member 14 in a closed position and to engage and hold capsule 6mounted in the cup shaped member of propeller 3. When cap 17 is inposition no air may be inhaled through the device and capsule 6 isfirmly held in position. When cap 17 is removed from the device, spring15 urges locking member 13 into its open position and air may be inhaledthrough the device with consequent rotation of propeller-like member 3and dispersal of the finely powdered medicament from capsule 6.

Around locking member 13 is disc 19 which serves as a nonreturn valvefor the device. Thus, if air is blown through the device disc 19 isurged against the end wall of housing 7 and closes air inlets l1 andthus prevents any further air from passing in that direction. If air issucked through the device, disc 19 is urged away from the end wall ofhousing 7, freeing inlets l I and thus allowing air to pass through thedevice.

The whole device may be constructed of any suitable materials,preferably of a synthetic thermoplastic resin such as nylon in whichcase it may be made by an injection moulding technique. In order thatthe shaft 2 and bearing tube should be in rolling contact it ispreferred to form tube 5 from an hard nylon and the shaft 2 from drawnwire.

As has been indicated above, the dimensions of the shaft and bearingaffect the precise form of motion generated by the above device and thatsatisfactory operation may be achieved by many permutations of thedimension. It is preferred to ensure that the clearance between theshaft and the narrow end of the bearing is less than about fivethousandths of an inch in order to minimize the effects which thisclearance will have on the dominant motion generated by the clearance atthe broad end of the bearing. Whilst it is generally preferred to use asthin a shaft as possible, a lower limit may be placed on the diameter ofthe shaft by rigidity considerations. In the present instance, the useof a drawn stainless steel shaft of uniform diameter of 0.080 inches andan hard nylon bearing with a top total clearance of 0.002 inches and abottom total clearance of 0.016 inches between the shaft and the bearingwall is found to give a satisfactory form of motion. The bearing has alength of about 0.5 inches which gives an included angle for thefrusto-cone of precession of approximately 2.

The forces acting on particles within the rotating capsule will varywith the diameter of the cone or frusto-cone of precession which itselfvaries along the length of the capsule. With the dimension given above,we have found that, for a capsule about 0.25 inches in diameter,satisfactory fluidization is achieved throughout the length of thecapsule if the capsule is mounted with the base of its parallel walledportion about 0.2 inches from the top end of the bearing.

It is emphasized that the specific dimensions given above represent butone of the many possible permutations that may be made to obtain adevice with essentially similar performance characterization.

In the device shown in FIG. 4 the shaft and bearing of the device ofFIG. 2 have been transposed. The bearing tube 5a is mounted co-axiallywith the housing and shaft 2a is mounted on the lower end of thepropellerlike device 3. Apart from this change, the construction andmethods of use of the devices are similar. However, it is interesting tonote that the transposed device generates an hypotrochoidal motionwhereas the non-transposed version generates an epitrochoidal motion.

The cosistently effective administration of a powdered material by thedevice of FIG. 2 has been confirmed by experimental trials carried outusing a bronchodilator as medicament in which the device was used toadminister over 1,000 doses of bronchodilator to some 30 persons and theresponse determined spirometrically. Inadequate response in any singlecase was found to be due to lack of response to the medicament itself,as confirmed by administration by alternative routes. In all other casesthe administration was found to be fully effective.

In the devices of FIGS. 1, 2, 3 and 4, the fact that there has beenclearance at eachend of the bearing has enabled the shaft to lie acrossthe bearing (rather than have to roll upon one wall of the bearing). Theshaft has therefore contacted the bearing tube at the widest andnarrowest parts only. FIG. 5 shows a further alternative form of bearingwhere lack of contact between the extremities of the bearing tube 5 isachieved by means of a lip 20 in the widest end of the bearing tube.This lip may be detachable e.g. by virtue of the fact that it is a snapfit into a co-operating recess in the bearing tube 5, or may be mouldedintegrally with the tube 5. The lip 20 may be made from the samematerial as the tube 5 or may be made from a friction pad material toassist rolling contact between the lip 20 and the shaft 2. In thislatter case the tube may be made from a low friction material, such aspolyfluorinated hydrocarbon resin, e.g. that sold under the RegisteredTrade Mark Teflon, in order to minimize the motion generated by theother end of the bearing tube.

FIG. 6 shows an alternative form of device which generates the motion ofthe method of the invention. This device comprises an elongated tubularhousing in two snap fit parts 24 and 25. Mounted in part 25 by means ofstruts 26 is a ball race through which an air stream may pass by meansof passages therethrough. In the ball race is journalled shaft 27substantially co-axial with the housing. Shaft 27 is joined by auniversal joint 28 to a shaft 29. Shaft 29 carries on its free end aboss 30 having a cup-like receptacle adapted to receive a powder capsulein a firm push fit. Between boss 30 and the universal joint 28, theshaft 29 is provided with an annular shoulder 31 having a roundedbearing face 32. The housing part 25 has mounted therein by struts 33 anannular bearing ring 34 around the inside surface of which bearing face32 may run. There is sufficient clearance between the inside of ring 34and shoulder 31 to permit the shaft 29 to be displaced through anextreme angle which corresponds with the desired included angle for thecone of precession. In order that slip between the face 32 and ring 34should not occur to an appreciable extent, the ring 34 is made from ahard nylon and the shoulder 32 from hardened steel.

The vanes necessary to drive the shaft 29 may be mounted either upon theboss 30 as shown or upon either of shafts 27 and 29.

Part 24 of the housing may be provided with a construction 35.

An alternative form of the restraining bearing for the device of FIG. 6is shown in FIG. 7. In this the annular shoulder 31 on shaft 29 is ofgreater diameter than ring 34 and is provided with a dependent skirt 36whose inner face bears against the outer face of ring 34. It isinteresting to note that this form of bearing produces an epitrochoidalmotion, whereas the device of FIG. 6 gives an hypotrochoidal motion.

The device of FIG. 8 is essentially identical to that shown in FIG. 6except that the pair of shafts 27 and 29 joined by the universal joint28 are replaced by a single flexible shaft 37 of circular cross sectionwhich whips during rotation and thus permits the free end of the shaft37 to rotate at an angle to the end of the shaft mounted in the ballrace. As the speed of rotation of the shaft 37 increases the free enddeflects further until the bearing face 32 of the shoulder 31 on theshaft 37 engages with annular bearing ring 34 and causes the rotatingshaft to process at the desired rate. As indicated earlier, the shaft 37may have a polygonal cross section, e.g. an hexagonal section. In suchan instance the annular bearing ring 34 and the shoulder 31 may bedispensed with.

FIG. 9 shows a fonn of shaft and bearing wherein the concept of atapered bearing tube is combined with the use of a restraining bearingring.

This device comprises an elongated tubular housing 38 within which ismounted a short rigid cylindrical shaft 39 by means of struts 40. Thefree end of shaft 39 is indented with a conical recess 41. A rotatableboss 42 is mounted co-axially upon a short rigid cylindrical shaft 43which is loosely journalled in the conical recess 41 in the end of shaft39. The boss 42 is also provided with a dependent annular skirt 44surrounding the shaft 43, which skirt has an internal diameter greaterthan the external diameter of shaft 39 and is of sufficient length thatits internal surface may engage with the exterior of shaft 39.

Boss 42 is provided with vanes 45, which are adapted to cause rotationof the boss upon the passage of air through the device, and with acup-like recess 46 adapted to receive a powder capsule in a push tightfit.

The housing 38 may be provided with an internal restriction 47 in orderto increase the air flow rate past a capsule mounted in recess 46.

When air is passed through the device, boss 42 is caused to rotate, andin view of the loose mounting of the short shaft 43 in the recess 41,the inner face of skirt 44 is caused to bear against shaft 39. Thecontact between shaft 39 and skirt 44 causes the boss to precess aroundits axis of precession. Whilst this contact must be frictional, andpreferably is a rolling contact, the contact between shaft 43 and recess41 may be lubricated in order to assist free rotation of the shaft 43. I

FIG. shows a device wherein precession of the axis of rotation of thecontainer is achieved other than by rolling contact between a rotatingand a stationary member. Such a device comprises an elongated tubularhousing 48 within the housing in a bearing bush 49 of cylindrical boremounted by struts 50 substantially co-axially with the housing 48.Within bush 49 is mounted rotatable cylindrical shaft 51, which may belubricated to assist its free rotation in the bush. The free end ofshaft 51 carries a boss 52 provided with vanes 53. Off center on boss 52is mounted a rigid cylindrical shaft 54 which carries a bearing tube 55of cylindrical bore which may be lubricated to assist its free rotationupon shaft 54. The tube 55 carries a boss 56 provided with vanes 57 andwith a receptacle 58, e. g. a cup shaped recess, adapted to receive apowder container in a push tight fit. The receptacle 58 is so orientatedthat a powder container is mounted upon boss 56 at an angle to the axisof tube 55.

If desired the housing 48 may be provided with a venturi 59 or any ofthe other further features provided in the device of FIG. 2 in order tooptimize its operation.

The passage of air through the device causes boss 52 to be rotated, thuscausing shaft 54 to precess about the axis of shaft 51; and causes boss56 to rotate which means that a container mounted thereon is caused torotate about an axis which is inclined to shaft 54 and is precessing byvirtue of the rotation of boss 52.

It will be appreciated that the device of FIG. 10 may be modified bymounting shaft 54 with its axis intersecting the axis of shaft 51, i.e.at an angle thereto. The receptacle 58 in the boss 56 may then beorientated so that a powder container is mounted therein co-axially withtube 55 rather than at an angle thereto.

in both the above forms of the device of FIG. 10, each shaft and bearingmay be lubricated in order to assist the rotation thereof.

We claim:

1. A method for dispensing a particulate medicament from a container,which comprises placing a container provided with at least one powderoutlet on one end of a rotatable member, supporting the rotatable memberonly at the other end a bearing means so shaped as to give to the axisof rotation of said rotatable member during rotation of the rotatablemember a path of precession which is contained within the generallyconical surface of precession and maintaining the axis of rotation ofthe container at an angle to the axis of the generally conical surfaceof precession while leaving the said one end of the rotatable memberfree, and pneumatically rotating said rotatable member for rotating thecontainer about an axis of the container for causing the walls of thecontainer to undergo repeated changes in radial acceleration withrespect to the generally conical surface of precession, which changes ofacceleration are of sufficient magnitude to overcome the centrifugal andcohesive forces which hold the particles in place upon the wall of thecontainer.

2. A method as claimed in claim 1 wherein the included angle of thegenerally conical surface of precession is from W to 60.

3. A method as claimed in claim 2 wherein the included angle is from 1to 5 4. A method as claimed in claim 1 wherein the effective motion of apoint on the container wall is a circular sequence of cusps leading intoone another at nodes, and the number of said nodes occurring perrotation of the container axis about the axis of the generally conicalsurface of precession is from 2 to 25.

5. A method as claimed in claim 4 wherein the number of nodes is from 3to 10.

6. A device for dispensing a particulate medicament material from acontainer, comprising a rotatable member having a free end and said freeend having means to receive the container, two cooperating bearingmeans, one bearing means being a shaft and the other being at least onebearing member within which said shaft is journalled, one of saidbearing means being on the end of said rotatable member opposite saidfree end and the other bearing means being fixed, said shaft and saidbearing member providing the sole support for said rotatable member andbeing so shaped as to give the axis of rotation of said rotatable memberduring rotation of the rotatable member a path of precession which iscontained within a generally conical surface of precession andmaintaining the axis of rotation of said rotatable member at an angle tothe axis of the generally conical surface of precession, and meansassociated with said rotatable member for pneumatically rotating it.

7. A device as claimed in claim 6 further comprising an elongatedtubular housing within which the rotatable member and the shaft andbearing member are mounted, one of said shaft and bearing member beingrigidly mounted substantially co-axially with the housing.

8. A device as claimed in claim 6 wherein the shaft and bearing memberare in frictional contact.

9. A device as claimed in claim 6 wherein the rotatable member has atleast one vane thereon for rotating the member upon the passage of a gasstream through the device.

10. A device as claimed in claim 6 which comprises a rotatable shaftmounted in a stationary bearing member, the free end of said shaftcarrying a universal joint, a further shaft connected to said firstshaft by means of said universal joint whereby the free end of saidfurther shaft may be displaced during rotation thereof at an angle aboutthe axis of said stationary bearing member, the free end of said furthershaft carrying means to receive a container, a stationary annularbearing member loosely encircling said further shaft, said annularbearing member and a portion of said further shaft contacting oneanother in a frictional contact during rotation of said further shaft.

11. A device as claimed in claim 10 wherein said further shaft and saidstationary annular bearing member contact one another in a rollingcontact at substantially all times during operation of the device.

12. A device as claimed in claim 6 in which the bearing member has anannular bearing surface and the shaft is journalled loosely in thebearing member, one of said shaft and said bearing being stationary, theother being on the rotatable member to be rotated by the pneumaticrotating means, the rotatable member being capable of being displacedduring rotation thereof at an angle about the axis of the stationarymember, the annular bearing surface of the bearing member and at least aportion of the shaft contacting one another in frictional contact duringrotation of the rotatable member.

13. A device as claimed in claim 12 wherein the bearing member is abearing tube contacting the shaft at both ends of the bearing tube.

14. A device as claimed in claim 13 wherein the shaft is a rigidsubstantially uniformly cylindrical shaft and the bearing tube is aninternally tapered bearing tube.

15. A device as claimed in claim 13 wherein the bearing tube has annularridges at at least one end thereof, said ridges providing an annularbearing surface against which the shaft bears.

16. A device as claimed in claim 13 wherein the diameter of the shaftand the internal diameter of the bearing tube at the contact betweenthat end of the bearing tube and the shaft generating the non-dominantmotion number for the nondominant motion of a point on the containerwall will have a value in excess of 15.

' relationship.

a/h (R /Rr) R, and the term exceeds the term R by a sufficient amount ofachieve fluidization of powder within a container mounted in the device,and wherein a is the distance of the base'of the parallel walled sectionof the container wall from the. non-dominant contact between the shaftand bearing tube, h is the distance between the dominant andnon-dominant contacts between shaft and bearing tube, R is the internalradius of the bearing tube at the dominant contact, r is theradius ofthe shaft and R is the in-' ternal radius of the container at the baseof the parallel walled section of the container wall.

19. A device as claimed in claim 13 in which a shaft is rotatablyjournalled in a stationary bearing tube and there is a dominantcontact-and a non-dominant contact between the shaft and bearing tube,the dominant contact being a rolling contact, the dimensions of thebearing tube and the shaftbeing in the relationship 7 a/lz (FIR- r) Rand the term a/h (r"/R-r) exceeds the term R by a sufficient amount toachieve fluidization ofpowder within a container mounted in the device;and wherein a is the distance of the base of the parallel walled sectionof the container wall from the non-dominant contact between the shaftand bearingtube, h is the distance between the dominant andnon-dominantcontacts between the shaft and bearing tube, R is theinternal radius of the bearing tube at the dominant contact, r is theradius of the shaft and R is the internal radius of the container at thebase of the parallel walled section of the container.

20. A device as claimed in claim 12 wherein the shaft is the stationarymember and the bearing member is the rotatable member.

21. A device as claimed in claim 12 in which the shaft is a rigidsubstantially uniform cylindrical shaft and the bearing member is aninternally tapered rotatable bearing tube which has an internal diameterat that end at which the free end of the shaft is positioned which issmaller than the internal diameter at its outer end.

22. A device as claimed in claim 21 wherein the bearing tube has aninternal diameter at the inner end which is from 1.5 to 6.0 percentgreater than the diameter of the shaft and an internal diameter at theouter end which is equal to the diameter of the shaft plus from 1.3 to3.5 percent of the internal length of the bearing tube.

23v A device as claimed in claim 22 wherein the bearing tube has aninternal length of from 4 to 10 times the diameter 'of the shaft.

24. A device as claimed in claim 11 wherein the shaft and bearing membercontact one another in a rolling contact at substantially all timesduring operation of the device.

25. A device as claimed in claim 6 further comprising a powder capsulemounted upon the rotatable member.

1. A method for dispensing a particulate medicament from a container, which comprises placing a container provided with at least one powder outlet on one end of a rotatable member, supporting the rotatable member only at the other end a bearing means so shaped as to give to the axis of rotation of said rotatable member during rotation of the rotatable member a path of precession which is contained within the generally conical surface of precession and maintaining the axis of rotation of the container at an angle to the axis of the generally conical surface of precession while leaving the said one end of the rotatable member free, and pneumatically rotating said rotatable member for rotating the container about an aXis of the container for causing the walls of the container to undergo repeated changes in radial acceleration with respect to the generally conical surface of precession, which changes of acceleration are of sufficient magnitude to overcome the centrifugal and cohesive forces which hold the particles in place upon the wall of the container.
 2. A method as claimed in claim 1 wherein the included angle of the generally conical surface of precession is from 1/2 * to 60*.
 3. A method as claimed in claim 2 wherein the included angle is from 1* to 5*
 4. A method as claimed in claim 1 wherein the effective motion of a point on the container wall is a circular sequence of cusps leading into one another at nodes, and the number of said nodes occurring per rotation of the container axis about the axis of the generally conical surface of precession is from 2 to
 25. 5. A method as claimed in claim 4 wherein the number of nodes is from 3 to
 10. 6. A device for dispensing a particulate medicament material from a container, comprising a rotatable member having a free end and said free end having means to receive the container, two cooperating bearing means, one bearing means being a shaft and the other being at least one bearing member within which said shaft is journalled, one of said bearing means being on the end of said rotatable member opposite said free end and the other bearing means being fixed, said shaft and said bearing member providing the sole support for said rotatable member and being so shaped as to give the axis of rotation of said rotatable member during rotation of the rotatable member a path of precession which is contained within a generally conical surface of precession and maintaining the axis of rotation of said rotatable member at an angle to the axis of the generally conical surface of precession, and means associated with said rotatable member for pneumatically rotating it.
 7. A device as claimed in claim 6 further comprising an elongated tubular housing within which the rotatable member and the shaft and bearing member are mounted, one of said shaft and bearing member being rigidly mounted substantially co-axially with the housing.
 8. A device as claimed in claim 6 wherein the shaft and bearing member are in frictional contact.
 9. A device as claimed in claim 6 wherein the rotatable member has at least one vane thereon for rotating the member upon the passage of a gas stream through the device.
 10. A device as claimed in claim 6 which comprises a rotatable shaft mounted in a stationary bearing member, the free end of said shaft carrying a universal joint, a further shaft connected to said first shaft by means of said universal joint whereby the free end of said further shaft may be displaced during rotation thereof at an angle about the axis of said stationary bearing member, the free end of said further shaft carrying means to receive a container, a stationary annular bearing member loosely encircling said further shaft, said annular bearing member and a portion of said further shaft contacting one another in a frictional contact during rotation of said further shaft.
 11. A device as claimed in claim 10 wherein said further shaft and said stationary annular bearing member contact one another in a rolling contact at substantially all times during operation of the device.
 12. A device as claimed in claim 6 in which the bearing member has an annular bearing surface and the shaft is journalled loosely in the bearing member, one of said shaft and said bearing being stationary, the other being on the rotatable member to be rotated by the pneumatic rotating means, the rotatable member being capable of being displaced during rotation thereof at an angle about the axis of the stationary member, the annular bearing surface of the bearing member and at least a portion of the shaft contacting one another in frictional contact during rotation of the rotatable member.
 13. A device as clAimed in claim 12 wherein the bearing member is a bearing tube contacting the shaft at both ends of the bearing tube.
 14. A device as claimed in claim 13 wherein the shaft is a rigid substantially uniformly cylindrical shaft and the bearing tube is an internally tapered bearing tube.
 15. A device as claimed in claim 13 wherein the bearing tube has annular ridges at at least one end thereof, said ridges providing an annular bearing surface against which the shaft bears.
 16. A device as claimed in claim 13 wherein the diameter of the shaft and the internal diameter of the bearing tube at the contact between that end of the bearing tube and the shaft generating the non-dominant motion number for the non-dominant motion of a point on the container wall will have a value in excess of
 15. 17. A device as claimed in claim 16 wherein the total clearance between the shaft and bearing tube at that end of the bearing tube generating the non-dominant motion is minimized at the non-dominant point of contact.
 18. A device as claimed in claim 13 in which a bearing tube is rotatably mounted on a stationary shaft, and there is a dominant contact and a non-dominant contact between the shaft and bearing tube, the dominant contact being a rolling contact, the dimensions of the bearing tube and shaft being in the relationship. a/h (R2/R-r) > Rc and the term a/h (R2/R-r) exceeds the term Rc by a sufficient amount of achieve fluidization of powder within a container mounted in the device, and wherein a is the distance of the base of the parallel walled section of the container wall from the non-dominant contact between the shaft and bearing tube, h is the distance between the dominant and non-dominant contacts between shaft and bearing tube, R is the internal radius of the bearing tube at the dominant contact, r is the radius of the shaft and Rc is the internal radius of the container at the base of the parallel walled section of the container wall.
 19. A device as claimed in claim 13 in which a shaft is rotatably journalled in a stationary bearing tube and there is a dominant contact and a non-dominant contact between the shaft and bearing tube, the dominant contact being a rolling contact, the dimensions of the bearing tube and the shaft being in the relationship a/h (r2/R-r) > Rc and the term a/h (r2/R-r) exceeds the term Rc by a sufficient amount to achieve fluidization of powder within a container mounted in the device; and wherein a is the distance of the base of the parallel walled section of the container wall from the non-dominant contact between the shaft and bearing tube, h is the distance between the dominant and non-dominant contacts between the shaft and bearing tube, R is the internal radius of the bearing tube at the dominant contact, r is the radius of the shaft and Rc is the internal radius of the container at the base of the parallel walled section of the container.
 20. A device as claimed in claim 12 wherein the shaft is the stationary member and the bearing member is the rotatable member.
 21. A device as claimed in claim 12 in which the shaft is a rigid substantially uniform cylindrical shaft and the bearing member is an internally tapered rotatable bearing tube which has an internal diameter at that end at which the free end of the shaft is positioned which is smaller than the internal diameter at its outer end.
 22. A device as claimed in claim 21 wherein the bearing tube has an internal diameter at the inner end which is from 1.5 to 6.0 percent greater than the diameter of the shaft and an internal diameter at the outer end which is equal to the diameter of the shaft plus from 1.3 to 3.5 percent of the internal length of the bearing tube.
 23. A device as Claimed in claim 22 wherein the bearing tube has an internal length of from 4 to 10 times the diameter of the shaft.
 24. A device as claimed in claim 11 wherein the shaft and bearing member contact one another in a rolling contact at substantially all times during operation of the device.
 25. A device as claimed in claim 6 further comprising a powder capsule mounted upon the rotatable member. 